If you want everything to fit it a browser window without a vertical scroll bar, you'll need the height of all the elements on the page to total 100%, which can be a problem when certain elements (like your Google ads) have an absolute height defined in pixels.
Since you are using frames, you could, perhaps, separate your Google ads from the SimpleViewer gallery and either put the ads in a separate frame or move them into the header.  This would allow your gallery (which you have defined to have a height of 100%) to fill one frame by itself without having to accommodate any other elements.

Alternatively, take a look at the instructions for Using a Resizable Gallery with a Header.
The sample galleries can be downloaded and modified.

Also, your page has several HTML errors which should be fixed.